1. Field of the Invention
The present invention relates to an application device and an application method for spraying a solvent for image formation onto an image recording material such as a photosensitive material or an image-receiving material or the like.
2. Description of the Related Art
There are image forming devices which carry out image recording processing by superposing, one on the other, an image-receiving material and a photosensitive material to which water has been applied as a solvent for image formation, and thermally processing the superposed materials. However, because water is applied by the photosensitive material being immersed in a tank in which water is stored, bacteria proliferate on the organic matter which has slightly eluded from photosensitive materials, and the water becomes dirty, causing image quality to deteriorate.
In order to solve such a problem, as illustrated in FIG. 8, a non-contact-type application device 104 has been proposed in which small water droplets are sprayed out from a plurality of nozzles 102 formed at a thin nozzle plate 100, such that the water droplets are applied to a photosensitive material 16.
A storing portion filled with water is provided at a spraying head 108 of the application device 104. By applying pressure to this storing portion, the water droplets are sprayed and atomized from the nozzles 102, and adhere to the photosensitive material 16.
At the spraying head 108, so-called overlapping spraying is carried out such that, even if one of the nozzles 102 becomes clogged or the position at which an atomized water droplet is shot is out of place, water can be applied uniformly to the photosensitive material 16.
Specifically, as illustrated in FIG. 9, staggered nozzles 102 which are disposed in 8 rows in the conveying direction of the photosensitive material (and are disposed symmetrically to the left and right of a central line C of the rows) are used. Each time the photosensitive material is conveyed in the direction of arrow A by a distance L corresponding to a length which is half of a row width, atomized water droplets are sprayed out.
Let us suppose that the nozzle corresponding to the blank circle w6 which is the third circle from the top in the sixth row is clogged. (The nozzles are actually continuous along a direction orthogonal to the conveying direction in a pattern of eight rows). Next, it will be considered to what extent the area of the photosensitive material 16, which should have originally had water applied thereto by the nozzle corresponding to the blank circle W6, can be covered the next time spraying is carried out (overlapping spraying).
As illustrated in FIG. 10A, looking at the surface of the photosensitive material on which water droplets have been shot, even if the blank circle W6 is clogged, water can be applied at hatched portions A1 at the peripheral blank circles W5, W6U, W6D, W7. Next, as illustrated in FIG. 10B, when overlapping spraying is carried out, the nozzles corresponding to a hatched circle B2U (the second circle in the second row) and a hatched circle B2D (the third circle in the second row) apply water to an area A2 (represented by hatching). As illustrated in FIGS. 10C and FIG. 11, the nozzles corresponding to a hatched circle B1 (the third circle in the first row) and a hatched circle B3 (the third circle in the third row) apply water to areas A3. In actuality, all of the circles overlap, but in order to be able to distinguish the respective circles, they are illustrated as separate from one another.
As a result, water is not applied to two substantially triangular areas A4, which are illustrated in white. Uneven application caused by nozzle clogging cannot be suppressed, and the application device cannot be made more reliable.
In view of the aforementioned, an object of the present invention is to provide an application device and application method in which uneven application due to nozzle clogging can be reduced without changing the density at which water droplets are shot.
In a first aspect of the present invention, an application device is provided with a plurality of nozzles which spray and apply a solvent for image formation onto an image recording material. The solvent is sprayed from the nozzles, in accordance with a moved amount of the image recording material, such that the positions on the image recording material at which the solvent is applied overlap one another. In this way, by carrying out so-called overlapping spraying, uneven application due to the clogging of a nozzle can be suppressed.
By spraying and applying solvent between rows of solvent which were previously sprayed and applied, even if one of the nozzles is clogged, the nozzles can apply the solvent to the greatest extent possible to the area of the image recording material to which the solvent should be applied.
In a second aspect of the present invention, the nozzles of the application device are disposed in 2m+1 rows, which is an odd number of rows, at intervals of L in the conveying direction of the image recording material, and are disposed in a staggered arrangement. Each time the image recording material is conveyed by a distance L(2m+1)/2, the solvent is sprayed. Note that m is an integer.
Because the nozzles are arranged as described above and because the solvent is sprayed at the timing described above, the solvent can be sprayed and applied between rows of solvent which were previously sprayed and applied. Further, by making the number of nozzle rows a odd number (2m+1), even if a nozzle becomes clogged and the position at which a drop of solvent is applied comes out of place, solvent can be applied uniformly.